OP,
I believe one point that people are trying really hard to make for you is that horses are prey animals and when frightened, their flight instinct takes over any and all training they have received. You cannot train instinct out of an animal, and I would be appalled if anyone even tried. This is the concept behind positive reinforcement vs. punishment methods, and why we are becoming less tolerant of methods using fear and punishment.
In your situation, your horse hit the electric wire accidentally. Period. No one intentionally drove it into the wire, and no amount of actual blanketing skills (expertise, credentials, licensure…) would have prevented the horse from touching the wire when it was so close to its face while eating and being blanketed simultaneously. A
What might have prevented the situation from happening is better overall barn management so that 1) horses do not eat near electric wires, or 2) horses who eat near electric wires are not blanketed while eating, or 3) the electric wires are turned off during feeding and blanketing time.
None of this has to do with the skill level of the blanketer. Once a horse is shocked, it’s going to react, whether it’s been trained to balance a circus ball on its nose or do Tempe changes wearing a tutu. A horse will be a horse, and the blanketer showed some skill in avoiding your horse.